Known mobile communications modules, such as GPRS modules, are used in PCMCIA cards. The modules include a number of integrated circuits that collectively function to allow information to be processed and transmitted in accordance with the required communications standard. In the case of GPRS modules the information is usually non-voice data, although voice data is transmitted similarly.
The design of portable computing devices such as laptop computers and PDA's is strongly driven to minimize while maximizing the period between recharging of the battery. This suggests that the battery should have as high an energy density as possible. However, batteries of this type typically have a high time constant and are therefore compromised in their ability to provide the required voltage and current during the high power mode of the typical communications modules used in these devices. Accordingly, the more usual compromise is to tolerate a lower power density—and therefore a shorter battery life—but gain a shorter time constant.
In partial answer to this problem, it has been known to use a bank of parallel tantalum capacitors to assist the battery during the high power mode. While some small advantage is gained, this is usually not justified by the cost and bulk of these capacitors.
The design of wireless communication devices for wireless LANs, PCMCIA cards and the like, is driven to achieve the desired functionality while also minimizing volume, peak power consumption and cost. In contrast, the demands for increased functionality and wider bandwidth communication usually require more volume, higher peak power and higher cost. These competing considerations place an increased premium on PCB “real estate”, packaging volumes and component costs as designers attempt to get more from less.
In any event, these cards are reliant upon the hots computing device supplying the required power. Increasingly it is being found that the host has a specified current limit for the card that is less than the peak current demanded. That is, for the card to operate it will have to do so outside the power supply specification of the host. While this may not be catastrophic in all cases, it is highly undesirable and, ultimately, unsustainable if system stability is required.
Accordingly, for both portable and mains supplied devices the increasing demands for communication flexibility is being compromised and hindered, if not prevented, by power supply limitations.
Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field.